Surgical stapling device for performing circular anastomosis and surgical staples for use therewith

ABSTRACT

The present disclosure relates to an anvil assembly, an end effector and/or a surgical stapler suitable for performing curved or circular anastomosis and/or treatment to internal walls of hollow tissue organs wherein the anvil assembly includes an anvil center rod having a proximal end and a distal end, the center rod defining a central longitudinal axis; and an anvil head secured to the distal end of the anvil center rod. The anvil head includes an anvil plate defining a tissue contact surface; and a plurality of staple forming pockets formed in the tissue contact surface of the anvil plate, wherein each of the plurality of staple pockets defines an arcuate longitudinal axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of and priority to each ofU.S. Provisional Patent Application Ser. No. 61/410,980, filed on Nov.8, 2010; and U.S. Provisional Patent Application Ser. No. 61/388,788,filed on Oct. 1, 2010, the entire contents of each of which beingincorporated herein by reference.

BACKGROUND

Technical Field

The present disclosure relates generally to a surgical stapling devicefor applying surgical staples to body tissue. More particularly, thepresent disclosure relates to a surgical stapling device suitable forperforming curved or circular anastomosis and/or treatment to internaltissue and/or to internal walls of hollow tissue organs.

Background of Related Art

Anastomosis is the surgical joining of separate hollow organ sections.Typically, an anastomosis procedure follows surgery in which a diseasedor defective section of hollow tissue is removed and the remaining endsections are to be joined. Depending on the desired anastomosisprocedure, the end sections may be joined by either circular, end-to-endor side-to-side organ reconstruction methods.

In a circular anastomosis procedure, the two ends of the organ sectionsare joined by means of a stapling instrument which drives a circulararray of staples through the end section of each organ section andsimultaneously cores any tissue interior of the driven circular array ofstaples to free the tubular passage. Examples of instruments forperforming circular anastomosis of hollow organs are described in U.S.Pat. Nos. 6,053,390, 5,588,579, 5,119,983, 5,005,749, 4,646,745,4,576,167, and 4,473,077, each of which is incorporated herein in itsentirety by reference. Typically, these instruments include an elongatedshaft having a handle portion at a proximal end to actuate theinstrument and a staple holding component disposed at a distal end. Ananvil assembly including an anvil rod with attached anvil head ismounted to the distal end of the instrument adjacent the staple holdingcomponent. Opposed end portions of tissue of the hollow organ(s) to bestapled are clamped between the anvil head and the staple holdingcomponent. The clamped tissue is stapled by driving one or more staplesfrom the staple holding component so that the ends of the staples passthrough the tissue and are deformed by the anvil head. The staples aredriven from the staple holding component by a pusher or pushers. Anannular knife is concurrently advanced to core tissue with the holloworgan to free a tubular passage within the organ.

Besides anastomosis of hollow organs, surgical stapling devices forperforming circular anastomosis have been used to treat internalhemorrhoids in the rectum. Typically, during use of a circular staplingdevice for hemorrhoid treatment, the anvil head and the staple holdingcomponent of the surgical stapling device are inserted through the anusand into the rectum with the anvil head and the staple holding componentin an open or unapproximated position. Thereafter, a purse-string sutureis used to pull the internal hemorrhoidal tissue towards the anvil rod.Next, the anvil head and the staple holding component are approximatedto clamp the hemorrhoid tissue between the anvil head and the stapleholding component. The stapling device is fired to remove thehemorrhoidal tissue and staple the cut tissue. A surgical stapler fortreating hemorrhoids is disclosed in Heinrich, U.S. Pat. No. 6,959,851,the disclosure of which is hereby incorporated by reference herein.

In circular stapling devices, typically a gap or spacing betweenadjacent staple forming pockets and corresponding staple retainingpockets, in each annular row, is greater for a radially outward row ascompared to a radially inward row. The staples have a straight backspanand the staple forming pockets and staple retaining pockets have astraight longitudinal axis. The inner annular row of staple formingpockets and/or staple retaining pockets determines the number of staplesfor each annular row. Each annular row has the same or equal number ofstaple forming pockets and/or staple retaining pockets. Accordingly, thegap between adjacent staple forming pockets and/or staple retainingpockets, in each annular row is greatest in the outer annular row ascompared to the inner annular row.

Accordingly, a need exists for providing a circular surgical staplingdevice wherein the gap between adjacent staple forming pockets and/orstaple retaining pockets, in each annular row is reduced or maintainedin each annular row thereof, from the outer annular row to internaltissue and/or to the inner annular row.

SUMMARY

The present disclosure relates to an anvil assembly, an end effectorand/or a surgical stapler suitable for performing curved or circularanastomosis and/or treatment to internal walls of hollow tissue organs.

According to an aspect of the present disclosure, an anvil assembly fora surgical stapling apparatus is provided. The anvil assembly includesan anvil center rod having a proximal end and a distal end, the centerrod defining a central longitudinal axis; and an anvil head secured tothe distal end of the anvil center rod. The anvil head includes an anvilplate defining a tissue contact surface; and a plurality of stapleforming pockets formed in the tissue contact surface of the anvil plate,wherein each of the plurality of staple pockets has a curved length.

The anvil assembly can have staple forming pockets wherein each stapleforming pocket has a radius of curvature extending from the centrallongitudinal axis of the center rod.

The anvil head may be circular, the anvil plate defining a plurality ofannular rows of staple forming pockets. Each annular row of stapleforming pockets can include an equal number of staple forming pockets.

A distance between adjacent staple forming pockets in each annular rowof staple forming pockets can be substantially equal for every annularrow of staple forming pockets. The anvil assembly can include stapleforming pockets wherein a length of each staple forming pocket of aninner annular row of staple forming pockets is relatively shorter than alength of each staple forming pocket of an outer annular row of stapleforming pockets.

The anvil plate can define at least two annular rows of staple formingpockets, or at least three annular rows of staple forming pockets. Incertain embodiments, the anvil plate defines an inner annular row ofstaple forming pockets, a middle annular row of staple forming pockets,and an outer annular row of staple forming pockets.

A length of each staple forming pocket of the middle annular row ofstaple forming pockets can be relatively longer than a length of eachstaple forming pocket of the inner annular row of staple formingpockets. A length of each staple forming pocket of the outer annular rowof staple forming pockets can be relatively longer than a length of eachstaple forming pocket of the middle annular row of staple formingpockets.

In certain embodiments, a distance between adjacent staple formingpockets in the inner annular row of staple forming pockets issubstantially equal to a distance between adjacent staple formingpockets in the middle annular row of staple forming pockets. A distancebetween adjacent staple forming pockets in the middle annular row ofstaple forming pockets can be substantially equal to a distance betweenadjacent staple forming pockets in the outer annular row of stapleforming pockets.

In certain embodiments, the staple forming pockets of at least twoadjacent annular rows of staple forming pockets are nested with oneanother. As such, the usage of a surface of the anvil is maximized forstaple capture. Additionally, the nesting of the at least two adjacentannular rows of staple forming pockets helps to maintain uniform radialand longitudinal spacing of the staples for even pressure distributionon the tissue.

According to another aspect of the present disclosure, an end effectorfor use with a surgical stapler is provided. The end effector comprisesanvil assembly including an anvil center rod having a proximal end and adistal end, the center rod defining a central longitudinal axis; and ananvil head secured to the distal end of the anvil center rod. The anvilhead includes an anvil plate defining a tissue contact surface; and aplurality of staple forming pockets formed in the tissue contact surfaceof the anvil plate, wherein each of the plurality of staple pockets hasa curved length. The end effector further includes a staple cartridgeassembly defining a plurality of staple retaining slots corresponding toa number of staple forming pockets of the anvil assembly, the staplecartridge assembly comprising a plurality of surgical staples supportedtherein in a spaced relation to each other.

In certain embodiments, each of the plurality of staple retaining slotsof the staple cartridge assembly has a curved length. Each stapleforming pocket of the anvil assembly can a radius of curvature extendingfrom the central longitudinal axis of the center rod. Each stapleretaining slot of the staple cartridge assembly may have a radius ofcurvature extending from a central longitudinal axis of the surgicalstapler.

The anvil assembly can be circular and define a plurality of annularrows of staple forming pockets, and the cartridge assembly can becircular and define a plurality of annular rows of staple retainingslots.

Each annular row of staple forming pockets of the anvil assembly caninclude an equal number of staple forming pockets. Each annular row ofstaple retaining slots of the staple cartridge assembly can include anequal number of staple retaining slots.

A distance between adjacent staple forming pockets in each annular rowof staple forming pockets of the anvil assembly can be substantiallyequal for every annular row of staple forming pockets. A distancebetween adjacent staple retaining clots in each annular row of stapleretaining slots of the staple cartridge assembly is substantially equalfor every annular row of staple forming pockets.

A length of each staple forming pocket of an inner annular row of stapleforming pockets of the anvil assembly can be relatively shorter than alength of each staple forming pocket of an outer annular row of stapleforming pockets of the anvil assembly. A length of each staple retainingslot of an inner annular row of staple retaining slots of the staplecartridge assembly can be relatively shorter than a length of eachstaple retaining slot of a middle annular row of staple retaining slotsof the staple cartridge assembly.

The anvil plate of the anvil assembly can define at least two annularrows of staple forming pockets, or at least three annular rows of stapleforming pockets. The staple cartridge assembly can define at least twoannular rows of staple retaining slots, or at least three annular rowsof staple retaining slots.

The anvil plate of the anvil assembly can define an inner annular row ofstaple forming pocket, a middle annular row of staple forming pocketsand an outer annular row of staple forming pockets. The staple cartridgeassembly can define an inner annular row of staple retaining slots, amiddle annular row of staple retaining slots and an outer annular row ofstaple retaining slots.

A length of each staple forming pocket of the middle annular row ofstaple forming pockets of the anvil assembly may be relatively longerthan a length of each staple forming pocket of the inner annular row ofstaple forming pockets of the anvil assembly. A length of each stapleforming pocket of the outer annular row of staple forming pockets of theanvil assembly may be relatively longer than a length of each stapleforming pocket of the middle annular row of staple forming pockets ofthe anvil assembly.

A length of each staple retaining slot of the middle annular row ofstaple retaining slots of the staple cartridge assembly can berelatively longer than a length of each staple retaining slot of theinner annular row of staple retaining slots of the staple cartridgeassembly. A length of each staple retaining slot of the outer annularrow of staple retaining slots of the staple cartridge assembly can berelatively longer than a length of each staple retaining slot of themiddle annular row of staple retaining slots of the staple cartridgeassembly.

A distance between adjacent staple forming pockets in the inner annularrow of staple forming pockets of the anvil assembly may be substantiallyequal to a distance between adjacent staple forming pockets in themiddle annular row of staple forming pockets of the anvil assembly. Adistance between adjacent staple forming pockets in the middle annularrow of staple forming pockets of the anvil assembly may be substantiallyequal to a distance between adjacent staple forming pockets in the outerannular row of staple forming pockets of the anvil assembly.

A distance between adjacent staple retaining slots in the inner annularrow of staple retaining slots of the staple cartridge assembly can besubstantially equal to a distance between adjacent staple retainingslots in the middle annular row of staple retaining slots of the staplecartridge assembly. A distance between adjacent staple retaining slotsin the middle annular row of staple retaining slots of the staplecartridge assembly can be substantially equal to a distance betweenadjacent staple retaining slots in the outer annular row of stapleretaining slots of the staple cartridge assembly.

The staple forming pockets of at least two adjacent annular rows ofstaple forming pockets of the anvil assembly may be nested with oneanother. The staple cartridge can include surgical staples that have acurved backspan.

Each staple retaining slot of each annular row of staple retaining slotsof the staple cartridge can be loaded with a surgical staple having abackspan with an appropriate length that corresponds to the length ofthe staple retaining slot. Each staple retaining slot of each annularrow of staple retaining slots of the staple cartridge can be loaded witha surgical staple having a backspan with an appropriate length thatcorresponds to the length of the staple retaining slot.

A length of the backspan of the surgical staples loaded in each stapleretaining slot of the middle annular row of staple retaining slots ofthe staple cartridge assembly can be relatively longer than a length ofthe backspan of the surgical staples loaded in each staple retainingslot of the inner annular row of staple retaining slots of the staplecartridge assembly. A length of the backspan of the surgical staplesloaded in each staple retaining slot of the outer annular row of stapleretaining slots of the staple cartridge assembly can be relativelylonger than a length of the backspan of the surgical staples loaded ineach staple retaining slot of the middle annular row of staple retainingslots of the staple cartridge assembly.

Each surgical staple can include a backspan and a leg depending fromeach opposed end of the backspan, wherein the legs define a plane, andwherein the backspan is arcuate and projects in a direction out of theplane defined by the legs of the surgical staple.

According to yet another aspect of the present disclosure, a surgicalstapler is provided and comprises a handle assembly including astationary handle, an approximation mechanism, and a firing trigger forfiring a plurality of surgical fasteners; and an end effector supportedon a distal end of the handle assembly. The end effector comprising ananvil assembly including an anvil center rod having a proximal endconfigured for selective connection to the approximation mechanism and adistal end, the center rod defining a central longitudinal axis; and ananvil head secured to the distal end of the anvil center rod. The anvilhead includes an anvil plate defining a tissue contact surface; and aplurality of staple forming pockets formed in the tissue contact surfaceof the anvil plate, wherein each of the plurality of staple pockets hasa curved length. The end effector further includes a staple cartridgeassembly defining a plurality of staple retaining slots corresponding toa number of staple forming pockets of the anvil assembly, the staplecartridge assembly comprising a plurality of surgical staples supportedtherein in a spaced relation to each other.

Each of the plurality of staple retaining slots of the staple cartridgeassembly may have a curved length.

Each staple forming pocket of the anvil assembly may have a radius ofcurvature extending from the central longitudinal axis of the centerrod. Each staple retaining slot of the staple cartridge assembly mayhave a radius of curvature extending from a central longitudinal axis ofthe surgical stapler.

The anvil assembly may be circular and may define a plurality of annularrows of staple forming pockets, and the cartridge assembly may becircular and may define a plurality of annular rows of staple retainingslots.

Each annular row of staple forming pockets of the anvil assembly mayinclude an equal number of staple forming pockets.

Each annular row of staple retaining slots of the staple cartridgeassembly may include an equal number of staple retaining slots.

A distance between adjacent staple forming pockets in each annular rowof staple forming pockets of the anvil assembly may be substantiallyequal for every annular row of staple forming pockets. A distancebetween adjacent staple retaining clots in each annular row of stapleretaining slots of the staple cartridge assembly may be substantiallyequal for every annular row of staple forming pockets.

A length of each staple forming pocket of a inner annular row of stapleforming pockets of the anvil assembly may be relatively shorter than alength of each staple forming pocket of a outer annular row of stapleforming pockets of the anvil assembly. A length of each staple retainingslot of a inner annular row of staple retaining slots of the staplecartridge assembly may be relatively shorter than a length of eachstaple retaining slot of a outer annular row of staple retaining slotsof the staple cartridge assembly.

The anvil plate of the anvil assembly may define at least two annularrows of staple forming pockets, or at least three annular rows of stapleforming pockets. The staple cartridge assembly may define at least twoannular rows of staple retaining slots, or at least three annular rowsof staple retaining slots.

The anvil plate of the anvil assembly may define an inner annular row ofstaple forming pocket, a middle annular row of staple forming pocketsand an outer annular row of staple forming pockets. The staple cartridgeassembly may define an inner annular row of staple retaining slots, amiddle annular row of staple retaining slots and an outer annular row ofstaple retaining slots.

A length of each staple forming pocket of the middle annular row ofstaple forming pockets of the anvil assembly may be relatively longerthan a length of each staple forming pocket of the inner annular row ofstaple forming pockets of the anvil assembly. A length of each stapleforming pocket of the outer annular row of staple forming pockets of theanvil assembly may be relatively longer than a length of each stapleforming pocket of the middle annular row of staple forming pockets ofthe anvil assembly.

A length of each staple retaining slot of the middle annular row ofstaple retaining slots of the staple cartridge assembly may berelatively longer than a length of each staple retaining slot of theinner annular row of staple retaining slots of the staple cartridgeassembly. A length of each staple retaining slot of the outer annularrow of staple retaining slots of the staple cartridge assembly may berelatively longer than a length of each staple retaining slot of themiddle annular row of staple retaining slots of the staple cartridgeassembly.

A distance between adjacent staple forming pockets in the inner annularrow of staple forming pockets of the anvil assembly may be substantiallyequal to a distance between adjacent staple forming pockets in themiddle annular row of staple forming pockets of the anvil assembly. Adistance between adjacent staple forming pockets in the middle annularrow of staple forming pockets of the anvil assembly may be substantiallyequal to a distance between adjacent staple forming pockets in the outerannular row of staple forming pockets of the anvil assembly.

A distance between adjacent staple retaining slots in the inner annularrow of staple retaining slots of the staple cartridge assembly may besubstantially equal to a distance between adjacent staple retainingslots in the middle annular row of staple retaining slots of the staplecartridge assembly. A distance between adjacent staple retaining slotsin the middle annular row of staple retaining slots of the staplecartridge assembly may be substantially equal to a distance betweenadjacent staple retaining slots in the outer annular row of stapleretaining slots of the staple cartridge assembly.

The staple forming pockets of at least two adjacent annular rows ofstaple forming pockets of the anvil assembly may be nested with oneanother.

Each staple retaining slot of each annular row of staple retaining slotsof the staple cartridge may be loaded with a surgical staple having abackspan with an appropriate length that corresponds to the length ofthe staple retaining slot.

Each staple retaining slot of each annular row of staple retaining slotsof the staple cartridge may be loaded with a surgical staple having abackspan with an appropriate length that corresponds to the length ofthe staple retaining slot. A length of the backspan of the surgicalstaples loaded in each staple retaining slot of the middle annular rowof staple retaining slots of the staple cartridge assembly may berelatively longer than a length of the backspan of the surgical staplesloaded in each staple retaining slot of the inner annular row of stapleretaining slots of the staple cartridge assembly. A length of thebackspan of the surgical staples loaded in each staple retaining slot ofthe outer annular row of staple retaining slots of the staple cartridgeassembly may be relatively longer than a length of the backspan of thesurgical staples loaded in each staple retaining slot of the middleannular row of staple retaining slots of the staple cartridge assembly.

Each staple may have a backspan that is curved. Each surgical staple mayinclude a backspan and a leg depending from each opposed end of thebackspan, wherein the legs define a plane, and wherein the backspan isarcuate and projects in a direction out of the plane defined by the legsof the surgical staple.

DESCRIPTION OF THE DRAWINGS

Various embodiment of the presently disclosed circular surgical staplingdevice are disclosed herein with reference to the drawings, wherein:

FIG. 1 is a perspective view of a circular surgical stapling deviceaccording to an embodiment of the present disclosure;

FIG. 2 is a rear perspective view of a prior art shell assembly andanvil assembly;

FIG. 3 is a front perspective view of the prior art anvil assembly andshell assembly of FIG. 2;

FIG. 4 is a perspective view of a prior art surgical staple;

FIG. 5 is a plan view of a tissue contact surface of an anvil plate ofthe anvil assembly of FIGS. 2 and 3;

FIG. 6 is an enlarged view of the indicated area of detail of FIG. 5;

FIG. 7 is a plan view of an anvil plate according to an embodiment ofthe present disclosure for use in an anvil assembly of a circularstapling device;

FIG. 8 is an enlarged view of the indicated area of detail of FIG. 7;

FIG. 9 is a schematic, longitudinal cross-sectional view of an anvilassembly and shell assembly according to another embodiment of thepresent disclosure;

FIG. 10 is a plan view of a tissue contact surface of a cartridgeassembly according to an embodiment of the present disclosure for use ina circular stapling device;

FIG. 11 is an enlarged view of the indicated area of detail of FIG. 10;

FIG. 12 is a plan view of a tissue contact surface of a cartridgeassembly according to another embodiment of the present disclosure foruse in a circular stapling device;

FIG. 13 is an enlarged view of the indicated area of detail of FIG. 12;

FIG. 14 is a perspective view of a surgical staple in accordance with anembodiment of the present disclosure for use in a circular staplingdevice;

FIG. 15 is an elevational view of the surgical staple of FIG. 14; and

FIG. 16 is a top, plan view of the surgical staple of FIGS. 14 and 15.

DETAILED DESCRIPTION OF EMBODIMENTS

Various exemplary embodiments of the presently disclosed anvil assemblyand cartridge assembly for a circular stapling device, will now bedescribed in detail with reference to the drawings wherein similarreference characters identify similar or identical elements. In thedrawings, and in the following description, the term “proximal” willrefer to the end of the anvil assembly, cartridge assembly or circularstapling device, or component thereof, that is closest to the operatorduring proper use, while the term “distal” will refer to the end that isfurthest from the operator, as is traditional and conventional in theart. In addition, the term “surgical fastener” should be understood toinclude any substantially rigid structure formed of a biocompatiblematerial that is suitable for the intended purpose of joining togetheradjacent tissue portions, including but not being limited to surgicalstaples, clips, two-part fasteners and the like.

FIG. 1 illustrates a circular stapling device, referred to generally bythe reference character 10. Briefly, surgical stapling device 10includes a handle assembly 12, an elongated central body portion 14extending from handle assembly 12, and a distal head portion 16supported on or at a distal end of central body portion 14. The lengthand/or configuration of the central body portion 14 may be altered orvaried to suit the requirements of the particular surgical procedure inwhich the surgical fastener applying apparatus may be employed. Forexample, the central body portion 14 may be either substantiallystraight, e.g., when intended for use in a procedure for the treatmentof hemorrhoids, or alternatively, the central body portion may becurved. The central body portion may be flexible. The transversedimensions of the body portion 14 and/or the head portion 16 may also bevaried to suit a particular surgical procedure.

The handle assembly 12 includes a stationary handle 20, a firing trigger22, and a rotatable approximation knob 24. The head portion 16 includesa shell assembly 130, and an anvil assembly 140. The shell assembly 130is configured, dimensioned, and adapted to accommodate a plurality ofsurgical fasteners 150, an example of which can be seen in FIG. 1, thatare used to attach adjacent portions of a patient's tissue. The staplesor other fasteners can be contained in a cartridge or loading unit. Theshell assembly 130 and the anvil assembly 140 of head portion 16includes additional components, and performs additional functions, eachof which is discussed in commonly assigned U.S. Pat. No. 7,234,624 toGresham et al., entitled “Surgical Stapling Device for PerformingCircular Anastomoses,” the entire content of which is incorporated byreference herein.

As seen in FIGS. 2, 3, 5 and 6, an anvil assembly according to the priorart is generally designated as 40. Anvil assembly 40 includes an anvilcenter rod assembly 42 and an anvil head assembly 44. As best seen inFIGS. 2 and 3, anvil center rod assembly 42 includes a center rod 42 aand, as seen in FIGS. 2, 5 and 6, anvil head assembly 44 includes ananvil head 44 a and an anvil plate 44 b defining three concentric,annular rows 46 a, 46 b, 46 c of respective staple forming pockets 48for receiving and forming staples.

As seen in FIGS. 5 and 6, each staple forming pocket 48 defines a linearor straight longitudinal axis “Y”. Also as seen in FIGS. 5 and 6, firstor inner annular row 46 a of staple forming pockets 48 is disposed alonga radius “R1,” second or middle annular row 46 b of staple formingpockets 48 is disposed along a radius “R2” greater than radius “R1,” andthird or outer annular row 46 c of staple forming pockets 48 is disposedalong a radius “R3” greater than radius “R2.” Each radius “R1”, “R2” and“R3” being measured relative to a midpoint of each staple forming pocket48.

As seen in FIGS. 5 and 6, since each staple forming pocket 48 defines alinear or straight longitudinal axis “Y,” a radial distance from ananastomosis lip 44 c of anvil head assembly 44 to each staple formingpocket 48 is not uniform or constant. In particular, a radial distance“AL₁” from anastomosis lip 44 c to a mid-point of each staple formingpocket 48 is less than a radial distance “AL₂” from anastomosis lip 44 cto either longitudinal end of each staple forming pocket 48.

Additionally, as seen in FIG. 6, since each staple forming pocket 48defines a linear or straight longitudinal axis “Y,” a radial distance“AL₃” between adjacent annular rows 46 a, 46 b, 46 c of staple formingpockets 48 is also not uniform or constant. In particular, for example,a radial distance “AL₃” from either longitudinal end of each stapleforming pocket 48 of a relatively radially inner annular row (e.g., 46a, 46 b) of staple forming pockets 48 to a mid-point of each stapleforming pocket 48 of a relatively radially outer annular row (e.g., 46b, 46 c) of staple forming pockets 48 is less than a radial distancefrom a mid-point of each staple forming pocket 48 of the relativelyradially outer annular row (e.g., 46 b, 46 c) of staple forming pockets48 to either longitudinal end of each staple forming pocket 48 of therelatively radially inner annular row (e.g., 46 c, 46 b) of stapleforming pockets 48.

Being that each annular row 46 a, 46 b and 46 c includes an equal numberof staple forming pockets 48 and being that each staple forming pocket48 has an equal length “L”, as seen in FIGS. 5 and 6, a distance betweenadjacent staple forming pockets 48, in each annular row 46 a, 46 b, 46c, increases as the radius of the annular row 46 a, 46 b, 46 cincreases. In particular, the first or inner annular row 46 a of stapleforming pockets 48 defines a first distance “Ga” between adjacent stapleforming pockets 48 thereof. The second or middle annular row 46 b ofstaple forming pockets 48 defines a second distance “Gb” betweenadjacent staple forming pockets 48 thereof that is greater than thefirst distance “Ga” between adjacent staple forming pockets 48 of firstor inner annular row 46 a. The third or outer annular row 46 c of stapleforming pockets 48 defines a third distance “Gc” between adjacent stapleforming pockets 48 thereof that is greater than the second distance “Gb”between adjacent staple forming pockets 48 of second or middle annularrow 46 b.

Additionally, since each staple forming pocket 48 has a straight orlinear shape, and since all the staple forming pockets 48 have a uniformor equal length “L”, a the radii (R1, R2, R3) of adjacent annular rows46 a, 46 b, 46 c has to be selected so that the staple forming pockets48 of one annular row 46 a, 46 b, 46 c do not interfere with the stapleforming pockets 48 of an adjacent annular row 46 a, 46 b, 46 c.

As best seen in FIG. 3, a staple cartridge assembly according to theprior art is generally designated as 30. Staple cartridge assembly 30includes a plurality of staple retaining slots 38 arranged in threeconcentric, annular rows 36 a, 36 b, 36 c. Each staple retaining slot 38is configured to retain a surgical staple therein. In order to properlycooperate with anvil assembly 40, cartridge assembly 30 includes anequal or corresponding number of staple retaining slots 38 as stapleforming pockets 46 of anvil assembly 40 that are in juxtaposed axialalignment with each other when anvil assembly 40 is connected tocircular stapling device 10.

As seen in FIG. 4, a surgical staple according to the prior art isgenerally designated as 50. Each surgical staple 50 includes a backspan52 and a pair of legs 54, 56 depending from opposed ends of backspan 52.As seen in FIG. 4, backspan 52 of surgical staple 50 is substantiallystraight and linear, wherein backspan 52 lies within a plane defined bylegs 54 and 56. Reference may be made to commonly owned and assignedU.S. Pat. No. 7,611,038 and U.S. Pat. No. 7,398,907, each entitled“Directionally Biased Staple and Anvil Assembly for Forming the Staple,”the entire content of each of which being incorporated herein byreference, for a detailed discussion of the surgical staple 50.

Reference may additionally be made to commonly assigned U.S. Pat. No.7,234,624 to Gresham et al., entitled “Surgical Stapling Device forPerforming Circular Anastomoses,” the entire content of which isincorporated by reference herein, for a detailed discussion andillustration of the operation and construction of circular staplingdevice 10. Generally, the anvil center rod is attached to an anvilretainer that is attached to a screw. Rotation of a knob retracts thescrew and anvil retainer to approximate the anvil and cartridgeassembly. A pivotable handle can be manipulated to advance a pusherlink, advancing pushers and a knife, forming staples against the anviland cutting tissue.

Reference may also be made to U.S. Patent Publication No. 2005/0187576,filed on Feb. 23, 2004, entitled “Surgical Cutting and Stapling Device,”the entire content of which is incorporated by reference herein, for adetailed discussion and illustration of the operation and constructionof a powered or electro-mechanical circular stapling device, that may beused with or may incorporate cartridge assemblies 130 and anvilassemblies 140 of the present disclosure, as discussed hereinbelow.

Turning now to FIGS. 1 and 5-16, a circular stapling deviceincorporating and/or for use with an end effector having a cartridgeassembly 130, an anvil assembly 140 and a surgical staple 150, inaccordance with the present disclosure, is shown and will be described.The handle assembly and elongated central body portion are substantiallyas described above. Alternatively, the end effector can be configured tobe utilized with a handle assembly and body portion, shaft and/oradapter that are configured with a motor or for use with a motor orother energy source.

As seen in FIGS. 7 and 8, an anvil assembly, in accordance an embodimentof the present disclosure, is generally designated as 140. Anvilassembly 140 includes an anvil head 144 a and an anvil plate 144 bdefining a plurality of concentric, annular rows 146 a, 146 b, 146 c ofrespective staple forming pockets 148 a, 148 b, 148 c for receiving andforming staples.

As seen in FIGS. 7 and 8, each staple forming pocket 148 defines anannular or arcuate longitudinal axis “Y1”. The staple forming pocketshave a curved, oblong shape. The curved length of each of the stapleforming pockets follows the shape of the arcuate face of the anvilplate. The staple forming pockets have a crescent, biconcave shape toreceive a staple having a curved backspan. Also as seen in FIGS. 7 and8, first or inner annular row 146 a of staple forming pockets 148 isdisposed along a radius “R4,” second or middle annular row 146 b ofstaple forming pockets 148 is disposed along a radius “R5” greater thanradius “R4,” and third or outer annular row 146 c of staple formingpockets 148 is disposed along a radius “R6” greater than radius “R5.”Each radius “R4”, “R5” and “R6” being measured relative to a midpoint ofeach staple forming pocket 148.

Since each staple forming pocket 148 defines an annular or arcuatelongitudinal axis “Y1”, a relative radial distance between radius “R4”and “R5” of respective first or inner annular row 146 a and second ormiddle annular row 146 b of anvil assembly 140 may be less than arelative radial distance between radius “R1” and “R2” of respectivefirst or inner annular row 46 a and second or middle annular row 46 b ofanvil assembly 40.

Additionally, a relative radial distance between radius “R5” and “R6” ofrespective second or middle annular row 146 b and third or outer annularrow 146 c of anvil assembly 140 may be less than a relative radialdistance between radius “R2” and “R3” of respective second or middleannular row 46 b and third or outer annular row 46 c of anvil assembly40. As such, the annular rows 146 a, 146 b and 146 c of staple formingpockets 148 a, 148 b, and 148 c may be more closely packed with respectto one another.

With continued reference to FIGS. 7 and 8, each staple forming pocket148 defines an annular or arcuate longitudinal axis “Ya, Yb and Yc” forrespective annular rows 146 a, 146 b, 146 c, and each annular row 146 a,146 b and 146 c includes an equal number of staple forming pockets 148.A length “La”, “Lb” and “Lc” for respective staple forming pockets 148a, 148 b, 148 c in respective annular rows 146 a, 146 b, 146 c mayincrease in a radially outward direction. In particular, the length “Lb”of staple forming pockets 148 b in second or middle annular row 146 bmay be greater than the length “La” of staple forming pockets 148 a infirst or inner annular row 146 a; and the length “Lc” of staple formingpockets 148 c in third or outer annular row 146 c may be greater thanthe length “Lb” of staple forming pockets 148 b in second or middleannular row 146 b.

In this manner, as seen in FIGS. 7 and 8, due to a difference in thelengths “La,” “Lb,” and “Lc” of respective staple forming pockets 148 a,148 b and 148 c, a distance between adjacent staple forming pockets 148a, 148 b, 148 c in each respective annular row 146 a, 146 b, 146 c maybe substantially equal. In particular, the first or inner annular row146 a of staple forming pockets 148 a defines a first distance “Ga”between adjacent staple forming pockets 148 a thereof. The second ormiddle annular row 146 b of staple forming pockets 148 b defines asecond distance “Gb” between adjacent staple forming pockets 148 bthereof that is substantially equal to the first distance “Ga” betweenadjacent staple forming pockets 148 a of first or inner annular row 148a. The third or outer annular row 146 c of staple forming pockets 148 cdefines a third distance “Gc” that is substantially equal to the firstdistance “Ga” between adjacent staple forming pockets 148 a of first orinner annular row 148 a and the second distance “Gb” between adjacentstaple forming pockets 148 b of second or middle annular row 148 b.

Additionally, each staple forming pocket 148 a, 148 b, 148 c may includea perimeterical profile or footprint having a central portion defined bya pair of parallel arcuate side walls interconnecting a pair of endportions defined by an enlarged bulbous or circular wall. Reference maybe made to commonly owned and assigned U.S. Pat. No. 7,611,038 and U.S.Pat. No. 7,398,907, each entitled “Directionally Biased Staple and AnvilAssembly for Forming the Staple,” the entire content of each of whichbeing incorporated herein by reference, for a detailed discussion of theend portions of staple forming pockets 148 a, 148 b, 148 c.

In this manner, as seen in FIGS. 7 and 8, staple forming pockets 148 a,148 b and 148 c of respective annular rows 146 a, 146 b and 146 c may benested with one another. The staple forming pockets can be formedutilizing stamping, coining, or other methods. Photolithography and/ormicroelectrolytic methods can be used. Microelectrolytic dissolution canbe used to form the staple forming pockets in the anvil plate so thatthe staple forming pockets have a curved length.

As seen in FIGS. 7 and 8, since each staple forming pocket 148 a, 148 b,148 c of respective annular rows 146 a, 146 b and 146 c defines anarcuate respective longitudinal axis “Ya, Yb, Yc,” a radial distancefrom an anastomosis lip 144 c of anvil head assembly 144 to each stapleforming pocket 148 a, 148 b, 148 c of respective annular rows 146 a, 146b and 146 c is substantially uniform or constant. In particular, aradial distance “AL₁” from anastomosis lip 144 c to a mid-point of eachstaple forming pocket 148 a, 148 b, 148 c of respective annular rows 146a, 146 b and 146 c is substantially equal to a radial distance “AL₂”from anastomosis lip 144 c to either longitudinal end of each stapleforming pocket 148 a, 148 b, 148 c of respective annular rows 146 a, 146b and 146 c.

Additionally, as seen in FIG. 7, since each staple forming pocket 148 a,148 b, 148 c of respective annular rows 146 a, 146 b and 146 c definesan arcuate respective longitudinal axis “Ya, Yb, Yc,” a radial distance“AL₃” between adjacent annular rows 146 a, 146 b, 146 c of stapleforming pockets 148 a, 148 b, 148 c is also substantially uniform orconstant. In particular, for example, a radial distance “AL₃” fromeither longitudinal end of each staple forming pocket 148 a, 148 b of arelatively radially inner annular row (e.g., 146 a, 146 b) of stapleforming pockets 148 to a mid-point of each staple forming pocket 148 b,148 c of a relatively radially outer annular row (e.g., 146 b, 146 c) ofstaple forming pockets 148 is less than a radial distance from amid-point of each staple forming pocket 148 b, 148 c of the relativelyradially outer annular row (e.g., 146 b, 146 c) of staple formingpockets 148 to either longitudinal end of each staple forming pocket 148c, 148 b of the relatively radially inner annular row (e.g., 146 c, 146b) of staple forming pockets 148.

As best seen in FIGS. 10 and 11, a staple cartridge assembly, inaccordance an embodiment of the present disclosure, is generallydesignated as 130. Staple cartridge assembly 130 includes a plurality ofstaple retaining slots 138 arranged in three concentric, annular rows136 a, 136 b, 136 c. Each staple retaining slot 138 is configured toretain a surgical staple therein. In order to properly cooperate withanvil assembly 140, cartridge assembly 130 includes an equal orcorresponding number of staple retaining slots 138 as staple formingpockets 148 of anvil assembly 140 that are in juxtaposed axial alignmentwith each other when anvil assembly 140 is connected to circularstapling device 10.

As seen in FIGS. 10 and 11, each staple retaining slot 138 defines anannular or arcuate longitudinal axis “Ya, Yb and Yc” for respectiveannular rows 136 a, 136 b, 136 c. The staple retaining slots have acurved, oblong shape. The curved length of each of the staple retainingslots follows the shape of the arcuate face of the cartridge assembly.The staple retaining slots have a crescent, biconcave shape to receive astaple having a curved backspan. Arcuate longitudinal axes “Ya, Yb andYc” of staple retaining slots 138 for respective annular rows 136 a, 136b, 136 c is substantially similar to or has a substantially similarradius of curvature as arcuate longitudinal axes “Ya, Yb and Yc” ofstaple forming pockets 148 for respective annular rows 146 a, 146 b, 146c. Also as seen in FIGS. 10 and 11, first or inner annular row 136 a ofstaple retaining slots 138 has a radius “R4,” second or middle annularrow 136 b of staple retaining slots 138 has a radius “R5” greater thanradius “R4,” and third or outer annular row 136 c of staple retainingslots 138 has a radius “R6” greater than radius “R5.” Each radius “R4”,“R5” and “R6” being measured relative to a midpoint of each stapleretaining slot 138. Additionally, the radius for each staple retainingslot 138 a, 138 b, 138 c for each annular row 136 a, 136 b, 136 c issubstantially constant or uniform along its entire length.

With continued reference to FIGS. 10 and 11, each staple retaining slot138 a, 138 b, 138 c defines respective annular or arcuate longitudinalaxis “Ya, Yb and Yc”, and annular row 136 a, 136 b and 136 c includes anequal number of staple retaining slots 138. A length “La”, “Lb” and “Lc”for respective staple retaining slots 138 a, 138 b, 138 c in respectiveannular rows 136 a, 136 b, 136 c may increase in a radially outwarddirection. In particular, the length “Lb” of staple retaining slots 138b in second or middle annular row 136 b may be greater than the length“La” of staple retaining slots 138 a in first or inner annular row 136a; and the length “Lc” of staple retaining slots 138 c in third or outerannular row 136 c may be greater than the length “Lb” of stapleretaining slots 138 b in second or middle annular row 136 b. In otherwords, each staple retaining slot 138 a, 138 b, 138 c in each respectiveannular row 136 a, 136 b, 136 c has a length that substantiallycorresponds to or relates to the lengths “La,” “Lb,” and “Lc” ofrespective staple forming pockets 148 a, 148 b and 148 c in eachrespective annular row 146 a, 146 b, 146 c.

In this manner, as seen in FIGS. 10 and 11, due to a difference in thelengths “La,” “Lb,” and “Lc” of respective staple retaining slots 138 a,138 b and 138 c, a distance between adjacent staple retaining slots 138a, 138 b and 138 c in each respective annular row 136 a, 136 b, 136 cmay be substantially equal. In particular, the first or inner annularrow 136 a of staple retaining slots 138 a defines a first distance “Ga”between adjacent staple retaining slots 138 a, the second or middleannular row 136 b of staple retaining slots 138 b defines a seconddistance “Gb” that is substantially equal to the first distance “Ga,”and the third or outer annular row 136 c of staple retaining slots 138 cdefines a third distance “Gc” that is substantially equal to the firstdistance “Ga” between adjacent staple retaining slots 138 a and thesecond distance “Gb” between adjacent staple retaining slots 138 b.

As seen in FIGS. 10 and 11, since each staple retaining slot 138 a, 138b, 138 c of respective annular rows 136 a, 136 b and 136 c defines anarcuate respective longitudinal axis “Ya, Yb, Yc,” a radial distancefrom an anastomosis lip 130 c of cartridge assembly 140 to each stapleretaining slot 138 a, 138 b, 138 c of respective annular rows 136 a, 136b and 136 c is substantially uniform or constant. In particular, aradial distance “AL₁” from anastomosis lip 130 c to a mid-point of eachstaple retaining slot 138 a, 138 b, 138 c of respective annular rows 136a, 136 b and 136 c is substantially equal to a radial distance “AL₂”from anastomosis lip 130 c to either longitudinal end of each stapleretaining slot 138 a, 138 b, 138 c of respective annular rows 136 a, 136b and 136 c.

Additionally, as seen in FIG. 11, since each staple retaining slot 138a, 138 b, 138 c of respective annular rows 136 a, 136 b and 136 cdefines an arcuate respective longitudinal axis “Ya, Yb, Yc,” a radialdistance “AL₃” between adjacent annular rows 136 a, 136 b, 136 c ofstaple retaining slots 138 a, 138 b, 138 c is also substantially uniformor constant. In particular, for example, a radial distance “AL₃” fromeither longitudinal end of each staple retaining slot 138 a, 138 b of arelatively radially inner annular row (e.g., 136 a, 136 b) of stapleretaining slots 138 to a mid-point of each staple retaining slot 138 b,138 c of a relatively radially outer annular row (e.g., 136 b, 136 c) ofstaple retaining slots 138 is less than a radial distance from amid-point of each staple retaining slot 138 b, 138 c of the relativelyradially outer annular row (e.g., 136 b, 136 c) of staple retainingslots 138 to either longitudinal end of each staple retaining slot 138c, 138 b of the relatively radially inner annular row (e.g., 136 c, 136b) of staple retaining slots 138.

Turning momentarily to FIG. 9, staple cartridge assembly, 130 may have astepped tissue contacting surface 140 a substantially similar to any ofthe tissue contacting surfaces shown and described in U.S. Pat. No.7,398,908, entitled “Surgical Stapling Instruments Including a Cartridgehaving Multiple Staple Sizes,” the entire content of which isincorporated herein by reference.

Turning now to FIGS. 12 and 13, staple forming pockets 248 for an anvilassembly 140, in accordance with another embodiment of the presentdisclosure are schematically shown and will be described. As seen inFIGS. 12 and 13, each staple forming pocket 248 defines a bent ornon-linear longitudinal axis in order to approximate a curved or arcuatelongitudinal axis. In particular, as seen in FIG. 13, each stapleforming pocket 248 includes at least a first segment 248 a defining afirst linear longitudinal axis “Y1” and a second segment 248 b defininga second linear longitudinal axis “Y2”, wherein the first segment 248 aand the second segment 248 b are angled with respect to one another byan angle “α.”

While FIGS. 12 and 13 have been described with relation to stapleforming pockets for an anvil assembly 140, it is contemplated and withinthe scope of the present disclosure apply substantially equally tostaple retaining slots for a staple cartridge assembly.

As seen in FIGS. 14-16, a surgical staple, in accordance withembodiments of the present disclosure, is generally designated as 150.Each surgical staple 150 includes a backspan 152 and a pair of legs 154,156 depending from opposed ends of backspan 152. As seen in FIGS. 14 and16, backspan 152 of surgical staple 150 is curved and defines an arcuatelongitudinal axis “Y3,” wherein backspan 152 extends out of a planedefined by legs 154 and 156. Arcuate longitudinal axis “Y3” of backspan152 of surgical staples 150 is substantially similar to or has asubstantially similar radius of curvature as arcuate longitudinal axis“Ya, Yb and Yc” of respective staple forming pockets 148 a, 148 b, 148 cand/or arcuate longitudinal axis “Ya, Yb, Yc” of staple retaining slots138 a, 138 b, 138 c.

Additionally, in accordance with the present disclosure, depending onwhich annular row 136 a, 136 b, 136 c of staple retaining slot 138 a,138 b, 138 c that surgical staple 150 is loaded, surgical staple 150will have a backspan 152 that has a length “La,” “Lb” or “Lc” thatcorresponds to the length “La”, “Lb” and “Lc” of respective stapleretaining slots 138 a, 138 b, 138 c. In particular, the surgical staples150 loaded in first or inner annular row 136 a of staple retaining slots138 a will have a backspan 152 with a length “La,” the surgical staples150 loaded in second or middle annular row 136 b of staple retainingslots 138 b will have a backspan 152 with a length “Lb,” and thesurgical staples 150 loaded in third or outer annular row 136 c ofstaple retaining slots 138 c will have a backspan 152 with a length“Lc.” It is contemplated that as a length “La”, “Lb” and “Lc” ofbackspan 152 of surgical staple 150 increases a corresponding length oflegs 154 and 156 of surgical staple 150 decreases such that an overalllength of material used to form surgical staples 150 loaded inrespective annular rows 136 a, 136 b, 136 c of staple retaining slots138 a, 138 b, 138 c remains substantially constant.

Moreover, as can be appreciated, in accordance with the presentdisclosure, the surgical staples 150 loaded in first or inner annularrow 136 a of staple retaining slots 138 a will have a backspan 152 witha radius of curvature “R4,” the surgical staples 150 loaded in second ormiddle annular row 136 b of staple retaining slots 138 b will have abackspan 152 with a radius of curvature “R5,” and the surgical staples150 loaded in third or outer annular row 136 c of staple retaining slots138 c will have a backspan 152 with a radius of curvature “R6.” Thepusher member (or members) for driving the staples will have individualpusher plates that are curved to correspond to the shape of the backspanof the staples.

The staple forming pockets and staple retention slots discussed abovehave an inner row of pockets (or slots) that are spaced the samedistance as an adjacent row of pockets (or slots) disposed outwardly ofthe inner row. As the spacing of the pockets (or slots) in the outwardlydisposed row has been decreased as compared to the device discussedabove in connection to FIGS. 2 through 4, a potential leak path issignificantly smaller.

For the surgical stapler, end effector, and/or anvil assembly discussedabove, two annular rows of surgical staples, two annular rows of stapleretention slots and two annular rows of staple forming pockets may beused. The annular rows can be circular, ovoid, semi-circular, or in theshape of an arc. Additionally, a longitudinal axis of each stapleretention slot and staple forming pocket may be angled or bent in orderto approximate an arc. The rows of staple retention slots and rows ofstaple forming pockets with curved lengths can be used in surgicalstaplers and end effectors that have linear jaws or jaws of othershapes.

While the above description contains many specifics, these specificsshould not be construed as limitations on the scope of the presentdisclosure, but merely as illustrations of various embodiments thereof.Therefore, the above description should not be construed as limiting,but merely as exemplifications of various embodiments. Those skilled inthe art will envision other modifications within the scope and spirit ofthe disclosure.

What is claimed:
 1. A surgical stapler, comprising: a handle assemblyincluding a stationary handle, an approximation mechanism, and a firingtrigger for firing a plurality of surgical fasteners; and an endeffector supported on a distal end of the handle assembly, the endeffector including: a circular anvil assembly, including: an anvilcenter rod having a proximal end configured for selective connection tothe approximation mechanism and a distal end, the center rod defining acentral longitudinal axis; and an anvil head secured to the distal endof the anvil center rod, the anvil head including: an anvil platedefining a tissue contact surface; and at least two annular rows of aplurality of staple forming pockets formed in the tissue contact surfaceof the anvil plate, wherein each of the plurality of staple formingpockets has a curved length, the length of each staple forming pocket ofa relatively inner annular row of staple forming pockets of the anvilassembly being relatively shorter than the length of each staple formingpocket of a relatively outer annular row of staple forming pockets ofthe anvil assembly; and a circular staple cartridge assembly defining atleast two rows of a plurality of staple retaining slots corresponding toa number of staple forming pockets of the anvil assembly, the staplecartridge assembly including a plurality of surgical staples supportedtherein in a spaced relation to each other.
 2. The surgical stapleraccording to claim 1, wherein each of the plurality of staple retainingslots of the staple cartridge assembly has a curved length.
 3. Thesurgical stapler according to claim 2, wherein each staple formingpocket of the anvil assembly has a radius of curvature extending fromthe central longitudinal axis of the center rod.
 4. The surgical stapleraccording to claim 3, wherein each staple retaining slot of the staplecartridge assembly has a radius of curvature extending from a centrallongitudinal axis of the surgical stapler.
 5. The surgical stapleraccording to claim 2, wherein the length of each staple retaining slotof a relatively inner annular row of staple retaining slots of thestaple cartridge assembly is relatively shorter than the length of eachstaple retaining slot of a relatively outer annular row of stapleretaining slots of the staple cartridge assembly.
 6. The surgicalstapler according to claim 5, wherein the anvil plate of the anvilassembly defines a middle annular row of staple forming pockets disposedbetween the inner annular row of staple forming pockets and the outerannular row of staple forming pockets.
 7. The surgical stapler accordingto claim 6, wherein the staple cartridge assembly defines a middleannular row of staple retaining slots disposed between the inner annularrow of staple retaining slots and the outer annular row of stapleretaining slots.
 8. The surgical stapler according to claim 7, whereinthe length of each staple forming pocket of the middle annular row ofstaple forming pockets of the anvil assembly is relatively longer thanthe length of each staple forming pocket of the inner annular row ofstaple forming pockets of the anvil assembly.
 9. The surgical stapleraccording to claim 8, wherein the length of each staple forming pocketof the outer annular row of staple forming pockets of the anvil assemblyis relatively longer than the length of each staple forming pocket ofthe middle annular row of staple forming pockets of the anvil assembly.10. The surgical stapler according to claim 9, wherein the length ofeach staple retaining slot of the middle annular row of staple retainingslots of the staple cartridge assembly is relatively longer than thelength of each staple retaining slot of the inner annular row of stapleretaining slots of the staple cartridge assembly.
 11. The surgicalstapler according to claim 10, wherein the length of each stapleretaining slot of the outer annular row of staple retaining slots of thestaple cartridge assembly is relatively longer than the length of eachstaple retaining slot of the middle annular row of staple retainingslots of the staple cartridge assembly.
 12. The surgical stapleraccording to claim 11, wherein a distance between adjacent stapleforming pockets in the inner annular row of staple forming pockets ofthe anvil assembly is substantially equal to a distance between adjacentstaple forming pockets in the middle annular row of staple formingpockets of the anvil assembly.
 13. The surgical stapler according toclaim 12, wherein the distance between adjacent staple forming pocketsin the middle annular row of staple forming pockets of the anvilassembly is substantially equal to a distance between adjacent stapleforming pockets in the outer annular row of staple forming pockets ofthe anvil assembly.
 14. The surgical stapler according to claim 13,wherein a distance between adjacent staple retaining slots in the innerannular row of staple retaining slots of the staple cartridge assemblyis substantially equal to a distance between adjacent staple retainingslots in the middle annular row of staple retaining slots of the staplecartridge assembly.
 15. The surgical stapler according to claim 12,wherein the distance between adjacent staple retaining slots in themiddle annular row of staple retaining slots of the staple cartridgeassembly is substantially equal to a distance between adjacent stapleretaining slots in the outer annular row of staple retaining slots ofthe staple cartridge assembly.
 16. The surgical stapler according toclaim 12, wherein the staple forming pockets of at least two adjacentannular rows of staple forming pockets of the anvil assembly are nestedwith one another.
 17. The surgical stapler according to claim 11,wherein each staple retaining slot of each annular row of stapleretaining slots of the staple cartridge assembly is loaded with asurgical staple having a backspan with an appropriate length thatcorresponds to the length of the staple retaining slot.
 18. The surgicalstapler according to claim 17, wherein the length of the backspan of thesurgical staples loaded in each staple retaining slot of the middleannular row of staple retaining slots of the staple cartridge assemblyis relatively longer than the length of the backspan of the surgicalstaples loaded in each staple retaining slot of the inner annular row ofstaple retaining slots of the staple cartridge assembly.
 19. Thesurgical stapler according to claim 18, wherein the length of thebackspan of the surgical staples loaded in each staple retaining slot ofthe outer annular row of staple retaining slots of the staple cartridgeassembly is relatively longer than the length of the backspan of thesurgical staples loaded in each staple retaining slot of the middleannular row of staple retaining slots of the staple cartridge assembly.20. The surgical stapler according to claim 19, wherein each surgicalstaple includes a leg depending from each opposed end of the backspan,wherein the legs define a plane, and wherein the backspan is arcuate andprojects in a direction out of the plane defined by the legs of thesurgical staple.
 21. The surgical stapler according to claim 1, whereineach annular row of staple forming pockets of the anvil assemblyincludes an equal number of staple forming pockets.
 22. The surgicalstapler according to claim 1, wherein each annular row of stapleretaining slots of the staple cartridge assembly includes an equalnumber of staple retaining slots.
 23. The surgical stapler according toclaim 22, wherein a distance between adjacent staple forming pockets ineach annular row of staple forming pockets of the anvil assembly issubstantially equal for every annular row of staple forming pockets. 24.The surgical stapler according to claim 23, wherein a distance betweenadjacent staple retaining slots in each annular row of staple retainingslots of the staple cartridge assembly is substantially equal for everyannular row of staple retaining slots.